Thermostatic control for fireplace damper



May 26, 1964 H. A. KANOY THERMOSTATIC CONTROL FOR FIREPLACE DAMPER 2Sheets-Sheet 1 Filed Nov. 21, 1961 y 1964 H. A. KANOY 3,134,377

THERMOSTATIC CONTROL FOR FIREPLACE DAMPER Filed Nov. 21, 1961 2Sheets-Sheet 2 I I INVENTOR: 9 HUBERT A. KAMOY ATTORNEYS United StatesPatent ()1 3,134,377 Patented May 26, 1964 ice 3,134,377 THERMOSTATICCONTROL FOR FREPLACE DAB [PER Hubert A. Kanoy, 506 S. Church St.,Salisbury, N.C. Filed Nov. 21, 1961, Ser. No. 153,984 7 Claims. (Cl.126288) The present invention relates generally to fireplace dampers andmore particularly to a thermally responsive auxiliary damper inassociation with a main fireplace damper to permit the products ofcombustion from smoldering portions or dying embers of a fire in thefireplace to be exhausted through the flue opening when the main damperhas been closed after the fire has been substantially extinguished.

A frequent annoyance associated with the use of fireplaces is thebacking-up of smoke, soot, and other products of combustion into theroom in which the fireplace is located, following the closing of theflue opening in the fireplace by the damper after a fire in thefireplace has been substantially extinguished. As is well known, theremains of an extinguished fire are apt to smolder for some time whichusually causes the person attending the fire to leave the damper openfor permitting the products of combustion from the smoldering portionsof the extinguished fire to escape through the flue opening in thefireplace. If the damper is immediately closed after the fire has beenput out, the aforesaid annoyance often ccurs and can create a firehazard as well as an atmospheric condition unfit for breathing. Sincethe smoldering portions or dying embers of the fire may continue tosmolder for a considerable period of time after the fire has beenextinguished or has burned itself out, a person attending the fire doesnot normally desire to remain on hand until the smoldering stops and thefire is completely dead so that the damper can then be closed.Consequently, the fire is usually left unattended after it has beensubstantially extinguished, and the damper is left open. When the dampertor the fireplace is left open, a considerable heat loss may ensuebecause of windy down drafts through the flue opening in the fireplaceand the escape of heat from the room through the open flue.

Accordingly, it is a primary object of the present invention to providean improved fireplace damper whose operation is affected by a thermallyresponsive control, wherein the damper comprises a main damper having avent therein coinciding with the flue opening of the fireplace and anauxiliary damper movable between positions closing and opening the ventin the main damper in response to changes of temperature in thefireplace, with the auxiliary damper being in position opening the ventwhen the temperature in the fireplace exceeds a predetermined magnitude(ambient room temperature). Thus, following the extinguishing of a firein the fireplace, the main damper may be immediately closed, theauxiliary damper being operable to maintain the vent open for exhaustingthe products of combustion from smoldering portions of the fire throughthe vent and the flue opening until the fire is completely dead. Uponthe temperature in the fireplace dropping to the predeterminedmagnitude, the auxiliary damper is effective to close the vent in themain damper. In this way, the hazards and annoyance associated with theblocking of smoke, soot, and other products of combustion from a fire ina fireplace by a damper closing the flue opening are avoided. Theimproved fireplace damper is also effective to avoid such blocking ofproducts of combustion when a fire has been started in the fireplace, aswell as when the fire has been extinguished, while any heat loss throughthe flue can be held to minimal levels by promptly closing the maindamper subsequent to extinguishing the fire and relying upon thethermally responsive auxiliary damper to eventually close the vent inthe main damper when the fire has completely died and no longersmolders.

The primary object of the invention having been stated, other objectswill appear as the description proceeds when taken in connection withthe accompanying drawings, in which- FIGURE 1 is a perspective view of afireplace in which an improved fireplace damper in accordance with thepresent invention is installed;

FIGURE 2 is a fragmentary vertical sectional view taken along the line2-2 of FIGURE 1, and showing the damper in a position closing the flueopening in the fireplace;

FIGURE 3 is a perspective view looking down on one form of damperassembly according to the present in vention and showing the main damperand the auxiliary damper associated in fully closed position;

FIGURE 4 is an enlarged transverse vertical sectional view taken alongthe line '44 in FIGURE 3, an open position of the auxiliary damper beingshown in phantom lines;

FIGURE 5 is a greatly enlarged fragmentary longitudinal sectional viewtaken along the line 5-5 in FIG- URE 4 and showing the thermostaticcontrol mechanism for the auxiliary damper;

FIGURE 6 is a transverse vertical sectional view taken along the line 66in FIGURE 5;

FIGURE 7 is a perspective view looking upward into another form ofdamper assembly according to the present invention and showing the maindamper and the auxiliary damper associated therewith in fully closedposition, parts of the auxiliary damper being illustrated in explodedrelation for purposes of clarity;

FIGURE 8 is an enlarged [fragmentary perspective view of a portion ofthe auxiliary damper illustrated in FIGURE 7, andshowing the positionassumed by a counterweighted strip thermostat when the auxiliary damperis in fully open position in phantom lines;

FIGURE 9 is an enlarged fragmentary vertical sectional view of thedamper assembly illustrated in FIG- URE 7, showing the auxiliary damperin fully closed position; and

FIGURE 10 is an enlarged fragmentary vertical sectional view similar toFIGURE 9, but showing the auxiliary damper in a position opening thevent through the main damper.

Referring more specifically to the drawings, one form of the improvedfireplace damper in accordance with the present invention is illustratedin FIGURES 1-6, inclusive. It will be observed that FIGURES 1 and 2 showa fireplace lt) with which the improved damper is associated, thefireplace 10 including a flue 11 through which the products ofcombustion from a fire in the fireplace 10 are exhausted in the usualmanner. A damper assembly 12 is mounted in the flue 11, the damperassembly 12 including a main damper plate, to be hereinafter described,which is mounted for movement between positions closing and opening theflue opening. The damper assembly 12 may be of any convenient type whichprovides a damper plate and means for manually moving the damper plateso as to close and open the flue opening.

As illustrated, the damper assembly 12 comprises a box-like frame 13formed by front and rear frame members 14, 15, end frame members 16, 16,and a marginal horizontal flange 17 integral with the lower edges of thefront, rear and end frame members-the marginal flange 17 being suitablyafiixed to the masonry construction of the fireplace 10, such as shownin FIGURE 2. It will be noted that the front and rear frame members 14,15 are disposed in upwardly converging relationship, the front than therear frame member 15 so as to provide the frame 13 with a rearwardly anddownwardly slanting top. The

' top of the frame 13 comprises an open rectangular top frame member 20forming a border extending inwardly of the respective top edges of thefront, rear, and end frame members so as to define an opening coincidingwith the flue opening when the damper assembly 12 is mounted in place inthe fireplace 19.

A main damper in the form of a main damper plate 21 is mounted forpivotal movement on the frame 13 between positions closing' and openingthe flue opening coinciding with the opening defined by the top framemember 29. In this connection, it will be observed that the main damperplate 21 is adapted to be superimposed over the inner portions of thetop frame member 20 when the main damper plate 21 is disposed in aposition closing the flue opening, with the lower edge of the maindamper plate 21 being pivotally connected to the corresponding lowerborder portion of the top frame member 20 by suitable means, such as theprojecting ears 22, 22 on the lower border portion'of the top framemember 20 to 'which the lower edge of the main damper plate 21 is.pivotally secured.

As shown in FIGURE 2, a curved handle 23 is attached to the undersurfaceof the main damper plate 21 so as to depend therefrom with the free endof the handle 23 being accessible from the front of the fireplace 10.The handle 23 includes a plurality of notches for respective receptionof a loop member 24 affixed to the damper assembly 7 general use.

In accordance with the present invention, it will-be observed,particularly in FIGURES 3 and 4, that an auxiliary damper means in theform of an auxiliary damper plate 36 for movement between positionsopening and closing the vent 31 in themain damper plate 21, 'andthermostatic control means within the fireplace 10 so as to efiect thedesired movement of the auxiliary damper plate 39. It will be observedthat the opposite ends of the auxiliary damper plate are connected tothe main damper plate 21.at the opposite ends of the vent31 for.

pivotal movement of the auxiliary damper plate 30 with respect to themain damper plate 21. In this respect, axles 35, 36 are fixedly securedto respective ends of the auxiliary damper plate 30 and extend outwardlytherefrom." The axle at one end of the auxiliary damper plate 3-0 isjournaled in a bearing block 37 secured to the main damper plate 21adjacent the end of the vent 31 corresponding to the axle 35. As willhereinafter appear, the axle 36 at the other end of the auxiliary damperplate 31 is also suitably journal-ed in a bearing element secured to themain damper plate 21 adjacent the opposite end of the vent 31.

broadly by the reference numeral 40 is disposed at the other end of theauxiliary damper plate 30 and comprises a segrnental housing 41. Thehousing 41 includes a pair of cup-like housing elements 42, 43 havingrespective cylindrical shells extending in opposite directions inopposed relationship. In the latter respect, the cylindrical shell ofcup-like housing element 43 is frictionally received within thecylindrical shell of cup-like housing eleor plate 34) is associated withthe main damper plate 21.

In this connection, the main damper plate 21 is provided with anelongate slot or vent 31 in the central portion thereof which is adaptedto be opened and closed by the auxiliary damper plate 30 in response tochanges in temperature in the fireplace 10 in a manner to be presentlydescribed.

It will be noted that upper and lower edge portions of the auxiliarydamper plate 30 are respectively offset in opposite directions from thecentral portion of the auxiliary damper plate 30 to form upper and lowerlip edges 33, 34. The upper lip edge 33 of theauxiliary damper plate 30is adapted to overlie a portion of the" main damper plate21 defining theupper boundary of the vent 31 therethrough, while the lower lip edge 34of the auxiliary damper plate 30 is adapted to underlie thecorresponding portion of the ,main damper plate 21 defining the lowerboundary of the vent 31 when the auxiliary damper' plate3l) is in aposition closing the vent 31 through the main damper plate 21, such asis shown in full lines in 7 FIGURE 4.

Means are provided to maketheauxiliary damper plate 30 movable betweenpos'itionsopening and closing the central vent 31 in the main damperplate 21 in response 'to changes of ,temperature in the fireplace 10. Inthis the tempe'rat'urein the fireplace ltl dropping to'the predeterminedmagnitude. To accomplish this end, the invention contemplatesthemounting of the auxiliary dampment 42 to define a chamber in which athermostat 44 is received. It will be observed in FIGURE 5 that theoutermost cup-like housing element 43 is provided with an inwardlyextending centrally disposed bearing sleeve 45 in which the axle 36 onthe other end of the auxiliary damper plate 30 is journaled. The housing41 is fixedly secured to the main damper plate- 21, the housing element43 being provided with mounting lugs 46, 46 for attachment of thehousing 41 tothe main damper plate 21 by suitable fastener meansextending through the lugs 46, 46.

.T he thermostat 44 is of the bimetallic strip type wound in a helicalcoil, being operably connected at its inner most end to the axle 36 ofthe auxiliary damper plate 30 mental housing 41. In this respect, a'radiallyinwardly 7 extending post 48 is secured to the cup-like housingelement 43, being provided with a threaded inner end for reception ofa'nut, and the outer'end of the helically coiled thermostat 44 issandwiched between the nutand an enlarged portion of the post 48 inclamped relationship. The inner and outer ends of'the thermostat 44 arepreferably notched for receiving the posts 47, 48 respectively. i

It will be understood that the helically coiled bimetal lic stripthermostat 44 expands in response to a rise of the temperature in thefireplace 10, as when afire is started therewithin, and correspondinglycontracts upon a drop of the temperature in thefireplace 10,-.as whenthe fire therein is extinguished. tracting, the thermostat 44 effectspivotal movement of the auxiliary damper plate 30 about its axles 35,36, which rotate within thebearing block 37 and the bearing sleeve 45respectively, the auxiliary damper-plate 36 being pivotally movablebetween positions in which the vent 31 through the main damper plate 21is opened in varying degrees of restriction, and a position in which theauxiliary damper plate30 closes the vent 31. The thermostat 44 and theauxiliary damper plate 30 are so ar-.

ranged as to effect closing of the vent 31 by the auxiliary Thethermostaic control means which is designated In so expandin'g'andcondamper plate 30 whenever the temperature within the fireplace dropsto a predetermined magnitude, such as a satisfactory ambient roomtemperatureas for example, 70 F. At all other times when the temperaturewithin the fireplace 10 exceeds this predetermined magnitude, thethermostat 44 will be in an expanded condition to some extent dependingupon the temperature within the fireplace 10, and the auxiliary damperplate 39 associated therewith will be in a position restrictivelyopening the vent 31 through the main damper plate 21 in varying degreesdepending upon the temperature Within the fireplace 10 in excess of thepredetermined temperature.

Thus, it will be seen that a person can immediately manually operate thedamper assembly 12 to move the main damper plate 21 to a positionclosing the flue opening by appropriate manipulation of the handle 23connected to the main damper plate 21, following the extinguishing of afire in the fireplace 10. At this time, the temperature present withinthe fireplace 10 will be in excess of the predetermined temperaturerequired to maintain the auxiliary damper plate 30 in a position closingthe vent 31. Accordingly, the thermostat 44 will be in an expandedcondition, and the auxiliary damper plate 30 will have been pivoted to aposition opening the vent 31 through the main damper plate 21, such asis shown in phantom lines in FIGURE 4. The products of combustion fromany smoldering portions of the fire are thereby permitted to escapethrough the flue 11 by passing through the open vent 31 in the maindamper plate 21. It therefore becomes unnecessary for a person attendingthe fire to make absolutely certain that the fire is completely out andto wait in the vicinity of the fireplace 10 until this event occursbefore closing the fireplace damper when an improved fireplace damperaccording to the present invention is installed in the fireplace 10. Theoften resorted-to alternative of leaving the fireplace damper in aposition opening the flue at all times during the period of the yearthat a fireplace is in frequent use with its consequent continual heatloss from the room in which the fireplace is located and accompanyingwindy downdrafts through the open flue 11 into the room is also avoidedby employing the improved fireplace damper herein disclosed inasmuch asthe auxiliary damper plate 39 will be moved to a position closing thevent 31 in the main damper plate 21, which itself has been earlier movedto a closed position following the substantial extinguishing of thefire, upon contraction of the helically coiled thermostat 44 when thetemperature within the fireplace 10 has dropped to a predeterminedmagnitude, such as ambient room temperature. 7

Another form ofimproved fireplace damper in accordance with the presentinvention is illustrated in FIGURES 7-10, inclusive. It will beunderstood that like reference numerals with the prime notation addedhave been applied in FIGURES 7-l0, inclusive, to indicate structuralcomponents similar to or identical with the structural components in theform of the invention shown in FIGURES l-6, inclusive. In FIGURES 7-10,inclusive, the thermostatic control means 40 comprises a unitarycup-like housing 41' removably secured to the undersurface of theauxiliary damper plate 30. Athermostat 44' is contained within thehousing 41, the thermostat 44' being in the form of athermally-responsive flexible flat elongate strip secured, to theundersurface of the auxiliary damper plate 30' by' a pin 50 dependingtherefrom to which one end of the elongate flat strip thermostat 44 isaffixed. The elongate strip thermostat 44 extends laterally from the pin'50, as illustrated in FIGURE 8, so as to be disposed beneath theauxiliary damper plate 30'. A counterweight element 51 in the form of acylindrical mass is aflixed to the other free end of the elongate stripthermostat 44'.

In this particular embodiment, the elongate strip thermostat 44' and thecounterweight 51 attached thereto will extend in a substantiallystraightforward path beneath the auxiliary damper plate 30' in spacedparallel relation thereto when the temperature within the fireplace isat a predetermined magnitude, such as ambient room temperature of theorder of 70 F. Upon a fire being started the fireplace, the heat of thefire will cause a rise of the temperature in the region of thefireplace, which induces flexing or bending of the elongate stripthermostat 44', such as illustrated in phantom lines in FIGURE 8. Thisflexing or bending of the elongate strip thermostat 44' under theinfluence of rising temperature effects the pivotal movement of theauxiliary damper plate 30" about its axles to a position opening thevent 31 in the main damper plate 21. In the latter connection, theauxiliary damper plate 30 with the thermostatic control means 40 affixedtherebeneath is disposed in a position closing the vent 31' when thetemperature within the fireplace is at a selected predeterminedmagnitude, such as ambient room temperature. It will be observed thatthe counterweight 51 is so located with respect to the auxiliary damperplate 30' as to tend to pivot the auxiliary damper plate 30 in acounterclockwise direction as shown in FIGURE 9, such pivoting movementof the auxiliary damper plate 30 being prevented by abutment of theupper and lower lip edges 33', 34' with the underlying and overlyingportions of the main damper plate 21 forming the upper and lowerboundaries of the vent 31 therethrough. However, whenever thetemperature within the fireplace exceeds the predetermined magnitude, aswhen a fire is started or as when the remains of an extinguished firecontinue to smolder, the flexing of the elongate strip thermostat 44'creates a tendency for the counterweight 51 to be moved to the right ofa vertical center-line passing through the pivotal axis of the auxiliarydamper plate 30, as shown in FIGURE 9', thereby upsetting theequilibrium of the auxiliary damper plate 30' in abutment with theportions of the main damper plate 21' bordering the upper and loweredges of the vent 31 therethrough. In this way, the flexed elongatestn'p thermostat 44' and its counterweight 51 efiect the pivotingmovementof the auxiliary damper plate 30' to a position opening the vent31, as shown in FIGURE '10, since the counterweight 51 will remain inalinement with the vertical center-line passing through the pivotal axisof the auxiliary damper plate 30'. The counterweight 51 because of itsweight and the influence of gravity is substantially stationary as theelongate strip thermostat 44' flexes in response to changes oftemperature in the fireplace, and the auxiliary damper plate '30" pivotsabout its axles to compensate for the flexing of the thermostat 44'which would otherwise dispose the counterweight 51 in an offset relationto the vertical center-line through the pivotal axis of the auxiliarydamper plate 30'. Thus, it will be understood that in operation, thesecond form of the improved fireplace damper in accordance with thepresent invention, as illustrated in FIGURES 7-'10, inclusive, achievesthe same desirable end results brought about by the first formillustrated in FIGURES 1-6, inelusive, and previously described.

It will therefore be seen that there has been disclosed an improvedfireplace damper, wherein a damper assemblyis provided with a maindamper plate having a vent therethrough which is adapted to be openedand closed by an auxiliary damper plate movable in response to changesof temperature in the fireplace. The improved fireplace dampercomprising the main damper plate and the auxiliary damper plateassociated with a thermostatic control means can be readily installed inexisting fireplaces by replacement of the old fireplace damper locatedtherein with the improved fireplace damper forming the presentinvention. It should be further understood that it is within the spiritof this invention to so locate the vent in the main damper plate thatthe auxiliary damper plate may be reciprocably movable in slidingrelationship to the main damper plate for accomplishing opening andclosing of the vent through the main damper plate in response to changesof temperature within the fireplace.

7 In the drawings and specification there have been set forth preferredembodiments of the invention and, although specific terms are employed,they are used in a generic and descriptive sense only and not forpurposes of limitation, the scope of the invention being defined in theclaims. a

, Icla-im:

1. In a fireplace having a flue opening and a damper plate mounted inthe fireplace for movement between positions closing and opening theflue opening;

' (a) said damper plate being provided with a vent therethrough,

(b) an auxiliary damper plate,

() means mounting said auxiliary damper plate for pivotal movementbetween positions closing and opening the vent in said damper plate,

((1) said auxiliary'damper plate having oppositely off 1 set side edgeportions engageable withcorresponding marginal portions of said damperplate bounding the sides of the vent therethrough in overlying andunder- 7 lying relation respectively when said auxiliary damper plate isdisposed in the position closing the vent in 'said damper plate,

(e) thermostatic control means operably associated with said auxiliarydamper platefor regulating the pivotal movement of said auxiliary damperplate in response to changes of temperature in the fireplace,

(f) said auxiliary damper plate being in a position opening the vent insaid damper plate when the temperature in the fireplace exceeds apredetermined magnitude, and

(g) said damper plate being movable to a position closing the flueopening when a fire in the fireplace has been extinguished and saidauxiliary damper plate being operable to maintain the vent open forexhausting the products of combustion from smoldering'por- 'tions of thefire through the ventin the damper plate and the flue opening until thetemperature in the fireplace drops tothe predetermined magnitude.

2. In a fireplace as defined in claim 1, wherein said thermostaticcontrol means comprises (a) van expandable and con'uactible helicallycoiled bimetallic strip thermostat,

(b) the inner end of said helically coiled-thermostat being operablyconnected to said auxiliary damper plate and the outer end of saidhelically coiled thermostat being operably connected to said damperplate,

and'

(c) said helically coiled thermostat expanding in'respouse to a rise oftemperature in the fireplace and contracting in response to a drop ofthe temperature in the fireplace to actuate pivotal movement of said 7auxiliary damper plate.

3. In a fireplaceas defined in claim 1, wherein said thermostaticcontrol means comprises i J (a) a'flexible elongated strip thermostat;

' (b) means connecting one end of said elongated strip thermostat tosaid auxiliary damper plate, and

(c) a counterweight on the other end of said elongated strip thermostat,a

(d) said elongated strip thermostat and said auxiliary damper platebeing disposed in spaced superimposed relationship, 7 v

(e) 'said. auxiliary damper plate being mounted for pivotalmovement'about a generally horizontal axis, and said counterweight lyingwithin avertical plane containing the pivotal axis of said auxiliarydamper plate, and I (1) said elongated strip thermostat flexing inresponse to changes of temperature-in the fireplace to actuateqpivotalmovement of said'auxilia ry damper plate which compensates forthe flexing of said elongated strip thermostat tending to dispose saidcounterweight in vertically otiset relation to the pivotal axis of saidauxiliary damper plate.

4. In a fireplace having a flue opening and a damper (a) said damperplate being provided with an elongate vent therethrough,

(b) an elongate auxiliary damper plate,

(c a pair of axles on said auxiliarydamper plate extending outwardlyfrom the opposite ends thereof, (d) bearing means on said damper platelocated adjacentthe opposite ends of the vent,

(2) .said axles being journaled in said bearing means to mount saidauxiliary damper plate for pivotal movement between positions closingand opening the vent in said damper plate,

(f) thermostatic control means operably associated with said auxiliarydamper plate for regulating the pivotal movement of said auxiliarydamper plate in response to changes of temperature in the fireplace, 1

and

(g) said auxiliary damper plate being in a position opening the vent insaid damper plate when the temperature in the fireplace exceeds apredetermined magnitude, I

(12) said damper plate being movable to a position closing the flueopening when a fire in the fireplace has been extinguished and saidauxiliary damper plate being operable to maintain the vent open forexhausting the products of combustion from smoldering portions of thefire through the vent in the damper plate and the flue opening until thetemperature in the fireplace drops to the predetrmined magnitude.

5. In a fireplace as defined in claim 4, wherein V (a) said thermostaticcontrol means is located at one end'of said auxiliary damper plate andthe end of the vent corresponding thereto, V v

(b) said thermostatic control means comprising a housing secured to'saiddamper plate and surround-. ing the axle extending from said one end ofsaid auxiliary damper plate, and

(c) an expandible and contractible'helically coiled'bimetallic stripthermostat within said housing, I

(d) the inner end of said helically coiled thermostat being operablyconnected to the axle extending from said one end of said auxiliarydamper plate and the outer end of said helically coiled thermostat beingoperably connected to said housing, I e

(e) the bearing means on said damper plate corresponding to the axleextending from said one end of said auxiliary damper plate beingdisposed within said housing for receiving the latter axle, and

(f) said helically coiled thermostat expanding in response to a rise oftemperature in the fireplace and contracting in response to a drop ofthe temperature in the fireplace to actuate pivotal movement of saidauxiliary damper plate.

said auxiliary damper plate and comprises (b) a housing secured to theundersurface of said auxiliary damper plate and received :in the ventthrpugh said damper plate,

(c) a flexible elongated strip thermostat within said" housing, 7 (d)means connecting one end ofsaid elongated strip thermostat to theundersurface of said auxiliary;

damper plate, and

(e) a counterweight on the other end of said elongated strip thermostat;

(f) said counterweight being vertically beneath thepiv- V 'otal axisofsaid auxiliary damper plate, and

' (g) said elongated strip thermostat flexing in response to changes oftemperature in the'fireplace' to actuate pivotal movement of saidauxiliary damper plate 7 which compensates for the flexing of saidelongated strip thermostat tending to dispose said counterweight invertically oflset relation to the pivotal axis of said auxiliary damperplate.

7. In a fireplace having a flue opening and a damper plate mounted inthe fireplace for movement between positions opening and closing theflue opening;

(a) said damper plate being provided with a vent therethrough,

(b) an auxiliary damper plate,

(a) means mounting said auxiliary damper plate for pivotal movementabout a generally horizontal axis between positions opening and closingthe vent in said damper plate,

(d) thermostatic control means operably associated with said auxiliarydamper plate for regulating the pivotal movement of said auxiliarydamper plate in response to changes of temperature in the fireplace,said thermostatic control means comprising (1) a flexible elongatedstrip thermostat,

(2) means connecting one end of said elongated strip thermostat to saidauxiliary damper plate to dispose said elongated strip thermostat andsaid auxiliary damper plate in spaced superimposed relationship, and

(3) a counterweight on the other end of said elongated strip thermostat,said counterweight lying within a vertical plane containing the pivotalaxis of said auxiliary damper plate;

(e) said elongated strip thermostat flexing in response to changes intemperature in the fireplace to actuate pivotal movement of saidauxiliary damper plate which compensates for the flexing of saidelongated strip thermostat tending to dispose said counterweight invertically ofiset relation to the pivotal axis of said auxiliary damperplate,

( said auxiliary damper plate being in a position opening the vent insaid damper plate when the temperature in the fireplace exceeds apredetermined magnitude, and

(g) said damper plate being movable to a position closing the flueopening when a fire in the fireplace has been extinguished and saidauxiliary damper plate being operable to maintain the vent open forexhausting the products of combustion from smoldering portions of thetire through the vent in the damper plate and the flue opening until thetemperature in the fireplace drops to the predetermined magnitude.

References Cited in the file of this patent UNITED STATES PATENTS1,010,790 Ogan Dec. 5, 1911 1,470,425 Curtis Oct. 9, 1923 1,549,231Stokes Aug. 11, 1925 1,798,431 McWilliams Mar. 31, 1931 1,928,577 Taroneet a1 Sept. 26, 1933 2,242,039 Mulcey et a1 May 13, 1941 2,262,460Johnson et al Nov. 11, 1941 2,797,874 Harding July 2, 1957

1. IN A FIREPLACE HAVING A FLUE OPENING AND A DAMPER PLATE MOUNTED INTHE FIREPLACE FOR MOVEMENT BETWEEN POSITIONS CLOSING AND OPENING THEFLUE OPENING; (A) SAID DAMPER PLATE BEING PROVIDED WITH A VENTTHERETHROUGH, (B) AN AUXILIARY DAMPER PLATE, (C) MEANS MOUNTING SAIDAUXILIARY DAMPER PLATE FOR PIVOTAL MOVEMENT BETWEEN POSITIONS CLOSINGAND OPENING THE VENT IN SAID DAMPER PLATE, (D) SAID AUXILIARY DAMPERPLATE HAVING OPPOSITELY OFFSET SIDE EDGE PORTIONS ENGAGEABLE WITHCORRESPONDING MARGINAL PORTIONS OF SAID DAMPER PLATE BOUNDING THE SIDESOF THE VENT THERETHROUGH IN OVERLYING AND UNDERLYING RELATIONRESPECTIVELY WHEN SAID AUXILIARY DAMPER PLATE IS DISPOSED IN THEPOSITION CLOSING THE VENT IN SAID DAMPER PLATE, (E) THERMOSTATIC CONTROLMEANS OPERABLY ASSOCIATED WITH SAID AUXILIARY DAMPER PLATE FORREGULATING THE PIVOTAL MOVEMENT OF SAID AUXILIARY DAMPER PLATE INRESPONSE TO CHANGES OF TEMPERATURE IN THE FIREPLACE, (F) SAID AUXILIARYDAMPER PLATE BEING IN A POSITION OPENING THE VENT IN SAID DAMPER PLATEWHEN THE TEMPERATURE IN THE FIREPLACE EXCEEDS A PREDETERMINED MAGNITUDE,AND (G) SAID DAMPER PLATE BEING MOVABLE TO A POSITION CLOSING THE FLUEOPENING WHEN A FIRE IN THE FIREPLACE HAS BEEN EXTINGUISHED AND SAIDAUXILIARY DAMPER PLATE BEING OPERABLE TO MAINTAIN THE VENT OPEN FOREXHAUSTING THE PRODUCTS OF COMBUSTION FROM SMOLDERING PORTIONS OF THEFIRE THROUGH THE VENT IN THE DAMPER PLATE AND THE FLUE OPENING UNTIL THETEMPERATURE IN THE FIREPLACE DROPS TO THE PREDETERMINED MAGNITUDE.